The present invention relates generally to the field of conduit liners and specifically to an apparatus and method for cutting service, or lateral, line openings in rehabilitative conduit liners using ultra-high pressured fluid. Of course, the technology of the present invention may be applied beyond this immediate setting in any application that demands cutting in confined areas and remote control and/or observation of such cutting.
The technology of rehabilitative conduit or pipe lining is well known in the prior art and in practice. Through relining, sewer lines may be rehabilitated without the need for expensive and labor-intensive subterranean digging, trench support installation, and the accompanying risk to workers. Relining is accomplished by inserting an uncured and typically xe2x80x9ccuffedxe2x80x9d pipe liner into a length of existing sewer pipe, everting the cuffed liner through application of mechanical, hydraulic, or other force, and allowing the liner, or a coating on the liner, to cure in place. Typical liners may be made of a felt or other carrier medium that is impregnated with uncured resin. Other liners may be folded or flattened PVC or polyethylene pipe that is reformed in situ through the application of pressure or heat or other extrusion means. In this manner, the inserted liner becomes a rigid and continuous pipe-within-a-pipe. Because the new lining is continuous, openings must be cut in the liner shortly after installation to return sewer service to existing homes or facilities whose service line connections are covered by the newly installed liner.
The known technology for returning service to existing service lines employs a remotely controlled sled which may be driven or pulled through a lined pipe and which includes a cutting arm. The cutting arm is longitudinally retractable from a typically cylindrical body and has on its end a rotary cutting blade or bit that may be used to cut through the liner at the points of service main connections.
Because service must quickly be returned to the sealed service line openings to prevent the back-up of sewage or waste through private service connections, the cutting often must occur before the recently installed liner is completely cured. The uncured liner, when exposed to the violence of the cutting process, showers uncured resin about the area of cutting. This uncured resin, along with other debris, may pollute remote sensing equipment. In particular, the resin and debris coats remote sensing equipment such as video camera lenses or other sensors (used to locate the points of service main connections, and to monitor the cutting process) and the surface of lights used to illuminate the cutting scene. Because the resin may become impossible or unduly burdensome to remove without causing damage to the sensors (if allowed to cure after arriving on a lens or sensor), workers must frequently withdraw the sensors from the confined space to a location, such as a manhole, where they may clear the sensor of resin and dirt manually or by other means. Then, workers must relocate the lateral service connection and continue the cutting operation. The process of repeated withdrawal, cleaning, and relocation dramatically increases the time and labor costs associated with pipe rehabilitation.
In addition to lost time due to the cleaning that is required in association with the use of a mechanical cutter, the mechanical cutters themselves demand frequent replacement or repair as the cutting bits become dull through use. Further, the mechanical cutters may contact original sewer lines and cause damage to the line or to the cutter blade.
A xe2x80x9cpolishingxe2x80x9d step is often required after a hole is cut with a mechanical cutter because the mechanical cutting element typically leaves rough edges in the pipe liner at the points of cutting. The polishing step entails withdrawing the sled, replacing the cutting bit with a sander, wire brush, or other smoothing element, relocating the openings, and smoothing out the rough edges. Whether through the cutting or the polishing step, the action of the bit upon the surface of the liner causes tremendous vibration of the cutter head, arm and sled. This vibration necessarily causes damage to even the most durable cutters, and cutter repair, rebuild and general xe2x80x9ctune upsxe2x80x9d are often necessary. Such repair or rebuilding may be necessary as frequently as every day of use. Therefore, the need for a separate polishing step in addition to the need for frequent repair of vibration-induced cutter damage further increases labor expense and lost opportunity.
In addition, all delays in the process increase the time during which service lines may be obstructed. There is therefore a need for a service line opening apparatus and method to eliminate or decrease downtime, decrease equipment maintenance and part replacement, decrease sewer wall damage, and decrease the overall time required to effect relining.
Examples of prior art rehabilitative pipe lining systems and liner cutters may be found in U.S. Pat. Nos. 4,197,908; 4,442,891; 4,577,388; and 4,630,676. In addition, prior art mechanical cutting systems have been manufactured by the Bowman Tool Co. of East Berlin, Pa. The ""908 patent issued Apr. 15, 1980 to Davis, et al., discloses a sled or carriage type cutting apparatus having a pneumatically driven mechanical cutting bit or blade and a television camera mounted on the carriage. The ""981 patent issued Apr. 17, 1984 to Wood, discloses a similar cutting device wherein the cutting element is maintained at a desired angle of intersection with the curved cutting surface through orbital motion or through a parallelogram-type linkage. The ""388 patent, issued Mar. 25, 1986 to Wood, discloses a method for the use of a computer to pre-program the contour of the wall to be cut for automatic control of the mechanical cutting element to maintain a desired angle of contact between the bit and the liner. Finally, the ""676 patent discloses a similar cutting apparatus wherein a mechanical cutting element is driven and manipulated axially, radially, and rotationally through the application of pressurized hydraulic fluid.
The present invention is a service line opener that uses xe2x80x9cintensifiedxe2x80x9d or xe2x80x9cultra-high-pressuredxe2x80x9d fluid, preferably water, as the cutting element. In addition to minimizing or eliminating the need for frequent withdrawal and replacement of damaged cutting blades, or potential damage to original sewer lines, the intensified water accomplishes a cut that is much smoother relative to the cut performed by the mechanical cutting bit. Therefore, the need for withdrawal to refit a polisher to the cutting head is eliminated. Further the fluid may be diverted in a more diffuse stream to a secondary function of setnsor, camera, or light-source cleaning. Alternatively, a source of water or fluid that is not intensified may be used to accomplish the secondary cleaning function. By combining the functions of liner cutting, finishing, and cleaning into the confined space operations rather than demanding individual steps separated by sled withdrawal and relocation, the time required to open a given length of liner and a given number of service lines is dramatically decreased. Further, the use of intensified water necessarily minimizes the vibration previously induced through mechanical means. Therefore, the need for withdrawal to repair the cutter and the ritualistic post-use rebuilding of the cutter is minimized. This decrease in time may dramatically decrease labor expenses and free equipment for use on a greater number of projects. Preferably, the present invention is practiced with a sled and monitor configuration. However, it will be understood by those skilled in the art that such a support/delivery system is merely an exemplary embodiment and that the benefits and functions of the present invention may extend to a plurality of other configurations.